<template>
  <div class="q-pa-md">
    <q-table
      flat bordered
      ref="tableRef"
      :class="tableClass"
      tabindex="0"
      title="Treats"
      :rows="rows"
      :columns="columns"
      row-key="name"
      selection="single"
      v-model:selected="selected"
      v-model:pagination="pagination"
      :filter="filter"
      @focusin="activateNavigation"
      @focusout="deactivateNavigation"
      @keydown="onKey"
    >
      <template v-slot:top-right>
        <q-input borderless dense debounce="300" v-model="filter" placeholder="Search">
          <template v-slot:append>
            <q-icon name="search" />
          </template>
        </q-input>
      </template>
    </q-table>
  </div>
</template>

<script>
import { ref, computed, nextTick, toRaw } from 'vue'

const columns = [
  {
    name: 'desc',
    required: true,
    label: 'Dessert (100g serving)',
    align: 'left',
    field: row => row.name,
    format: val => `${val}`,
    sortable: true
  },
  { name: 'calories', align: 'center', label: 'Calories', field: 'calories', sortable: true },
  { name: 'fat', label: 'Fat (g)', field: 'fat', sortable: true },
  { name: 'carbs', label: 'Carbs (g)', field: 'carbs' },
  { name: 'protein', label: 'Protein (g)', field: 'protein' },
  { name: 'sodium', label: 'Sodium (mg)', field: 'sodium' },
  { name: 'calcium', label: 'Calcium (%)', field: 'calcium', sortable: true, sort: (a, b) => parseInt(a, 10) - parseInt(b, 10) },
  { name: 'iron', label: 'Iron (%)', field: 'iron', sortable: true, sort: (a, b) => parseInt(a, 10) - parseInt(b, 10) }
]

const rows = [
  { id: 1, name: 'Frozen Yogurt', calories: 159, fat: 6.0, carbs: 24, protein: 4.0, sodium: 87, calcium: '14%', iron: '1%' },
  { id: 2, name: 'Ice cream sandwich', calories: 237, fat: 9.0, carbs: 37, protein: 4.3, sodium: 129, calcium: '8%', iron: '1%' },
  { id: 3, name: 'Eclair', calories: 262, fat: 16.0, carbs: 23, protein: 6.0, sodium: 337, calcium: '6%', iron: '7%' },
  { id: 4, name: 'Cupcake', calories: 305, fat: 3.7, carbs: 67, protein: 4.3, sodium: 413, calcium: '3%', iron: '8%' },
  { id: 5, name: 'Gingerbread', calories: 356, fat: 16.0, carbs: 49, protein: 3.9, sodium: 327, calcium: '7%', iron: '16%' },
  { id: 6, name: 'Jelly bean', calories: 375, fat: 0.0, carbs: 94, protein: 0.0, sodium: 50, calcium: '0%', iron: '0%' },
  { id: 7, name: 'Lollipop', calories: 392, fat: 0.2, carbs: 98, protein: 0, sodium: 38, calcium: '0%', iron: '2%' },
  { id: 8, name: 'Honeycomb', calories: 408, fat: 3.2, carbs: 87, protein: 6.5, sodium: 562, calcium: '0%', iron: '45%' },
  { id: 9, name: 'Donut', calories: 452, fat: 25.0, carbs: 51, protein: 4.9, sodium: 326, calcium: '2%', iron: '22%' },
  { id: 10, name: 'KitKat', calories: 518, fat: 26.0, carbs: 65, protein: 7, sodium: 54, calcium: '12%', iron: '6%' },
  { id: 11, name: 'Frozen Yogurt-1', calories: 159, fat: 6.0, carbs: 24, protein: 4.0, sodium: 87, calcium: '14%', iron: '1%' },
  { id: 12, name: 'Ice cream sandwich-1', calories: 237, fat: 9.0, carbs: 37, protein: 4.3, sodium: 129, calcium: '8%', iron: '1%' },
  { id: 13, name: 'Eclair-1', calories: 262, fat: 16.0, carbs: 23, protein: 6.0, sodium: 337, calcium: '6%', iron: '7%' },
  { id: 14, name: 'Cupcake-1', calories: 305, fat: 3.7, carbs: 67, protein: 4.3, sodium: 413, calcium: '3%', iron: '8%' },
  { id: 15, name: 'Gingerbread-1', calories: 356, fat: 16.0, carbs: 49, protein: 3.9, sodium: 327, calcium: '7%', iron: '16%' },
  { id: 16, name: 'Jelly bean-1', calories: 375, fat: 0.0, carbs: 94, protein: 0.0, sodium: 50, calcium: '0%', iron: '0%' },
  { id: 17, name: 'Lollipop-1', calories: 392, fat: 0.2, carbs: 98, protein: 0, sodium: 38, calcium: '0%', iron: '2%' },
  { id: 18, name: 'Honeycomb-1', calories: 408, fat: 3.2, carbs: 87, protein: 6.5, sodium: 562, calcium: '0%', iron: '45%' },
  { id: 19, name: 'Donut-1', calories: 452, fat: 25.0, carbs: 51, protein: 4.9, sodium: 326, calcium: '2%', iron: '22%' },
  { id: 20, name: 'KitKat-1', calories: 518, fat: 26.0, carbs: 65, protein: 7, sodium: 54, calcium: '12%', iron: '6%' },
  { id: 21, name: 'Frozen Yogurt-2', calories: 159, fat: 6.0, carbs: 24, protein: 4.0, sodium: 87, calcium: '14%', iron: '1%' },
  { id: 22, name: 'Ice cream sandwich-2', calories: 237, fat: 9.0, carbs: 37, protein: 4.3, sodium: 129, calcium: '8%', iron: '1%' },
  { id: 23, name: 'Eclair-2', calories: 262, fat: 16.0, carbs: 23, protein: 6.0, sodium: 337, calcium: '6%', iron: '7%' },
  { id: 24, name: 'Cupcake-2', calories: 305, fat: 3.7, carbs: 67, protein: 4.3, sodium: 413, calcium: '3%', iron: '8%' },
  { id: 25, name: 'Gingerbread-2', calories: 356, fat: 16.0, carbs: 49, protein: 3.9, sodium: 327, calcium: '7%', iron: '16%' },
  { id: 26, name: 'Jelly bean-2', calories: 375, fat: 0.0, carbs: 94, protein: 0.0, sodium: 50, calcium: '0%', iron: '0%' },
  { id: 27, name: 'Lollipop-2', calories: 392, fat: 0.2, carbs: 98, protein: 0, sodium: 38, calcium: '0%', iron: '2%' },
  { id: 28, name: 'Honeycomb-2', calories: 408, fat: 3.2, carbs: 87, protein: 6.5, sodium: 562, calcium: '0%', iron: '45%' },
  { id: 29, name: 'Donut-2', calories: 452, fat: 25.0, carbs: 51, protein: 4.9, sodium: 326, calcium: '2%', iron: '22%' },
  { id: 30, name: 'KitKat-2', calories: 518, fat: 26.0, carbs: 65, protein: 7, sodium: 54, calcium: '12%', iron: '6%' },
  { id: 31, name: 'Frozen Yogurt-3', calories: 159, fat: 6.0, carbs: 24, protein: 4.0, sodium: 87, calcium: '14%', iron: '1%' },
  { id: 32, name: 'Ice cream sandwich-3', calories: 237, fat: 9.0, carbs: 37, protein: 4.3, sodium: 129, calcium: '8%', iron: '1%' },
  { id: 33, name: 'Eclair-3', calories: 262, fat: 16.0, carbs: 23, protein: 6.0, sodium: 337, calcium: '6%', iron: '7%' },
  { id: 34, name: 'Cupcake-3', calories: 305, fat: 3.7, carbs: 67, protein: 4.3, sodium: 413, calcium: '3%', iron: '8%' },
  { id: 35, name: 'Gingerbread-3', calories: 356, fat: 16.0, carbs: 49, protein: 3.9, sodium: 327, calcium: '7%', iron: '16%' },
  { id: 36, name: 'Jelly bean-3', calories: 375, fat: 0.0, carbs: 94, protein: 0.0, sodium: 50, calcium: '0%', iron: '0%' },
  { id: 37, name: 'Lollipop-3', calories: 392, fat: 0.2, carbs: 98, protein: 0, sodium: 38, calcium: '0%', iron: '2%' },
  { id: 38, name: 'Honeycomb-3', calories: 408, fat: 3.2, carbs: 87, protein: 6.5, sodium: 562, calcium: '0%', iron: '45%' },
  { id: 39, name: 'Donut-3', calories: 452, fat: 25.0, carbs: 51, protein: 4.9, sodium: 326, calcium: '2%', iron: '22%' },
  { id: 40, name: 'KitKat-3', calories: 518, fat: 26.0, carbs: 65, protein: 7, sodium: 54, calcium: '12%', iron: '6%' }
]

export default {
  setup () {
    const tableRef = ref(null)

    const navigationActive = ref(false)
    const pagination = ref({})
    const selected = ref([])

    return {
      tableRef,

      navigationActive,
      filter: ref(''),
      selected,
      pagination,

      columns,
      rows,

      tableClass: computed(() => navigationActive.value === true ? 'shadow-8 no-outline' : null),

      activateNavigation () {
        navigationActive.value = true
      },

      deactivateNavigation () {
        navigationActive.value = false
      },

      onKey (evt) {
        if (
          navigationActive.value !== true ||
          [ 33, 34, 35, 36, 38, 40 ].indexOf(evt.keyCode) === -1 ||
          tableRef.value === null
        ) return

        evt.preventDefault()

        const { computedRowsNumber, computedRows } = tableRef.value

        if (computedRows.length === 0) return

        const currentIndex = selected.value.length > 0 ? computedRows.indexOf(toRaw(selected.value[ 0 ])) : -1
        const currentPage = pagination.value.page
        const rowsPerPage = pagination.value.rowsPerPage === 0 ? computedRowsNumber : pagination.value.rowsPerPage
        const lastIndex = computedRows.length - 1
        const lastPage = Math.ceil(computedRowsNumber / rowsPerPage)

        let index = currentIndex
        let page = currentPage

        switch (evt.keyCode) {
          case 36: // Home
            page = 1
            index = 0
            break
          case 35: // End
            page = lastPage
            index = rowsPerPage - 1
            break
          case 33: // PageUp
            page = currentPage <= 1 ? lastPage : currentPage - 1
            if (index < 0) {
              index = 0
            }
            break
          case 34: // PageDown
            page = currentPage >= lastPage ? 1 : currentPage + 1
            if (index < 0) {
              index = rowsPerPage - 1
            }
            break
          case 38: // ArrowUp
            if (currentIndex <= 0) {
              page = currentPage <= 1 ? lastPage : currentPage - 1
              index = rowsPerPage - 1
            }
            else {
              index = currentIndex - 1
            }
            break
          case 40: // ArrowDown
            if (currentIndex >= lastIndex) {
              page = currentPage >= lastPage ? 1 : currentPage + 1
              index = 0
            }
            else {
              index = currentIndex + 1
            }
            break
        }

        if (page !== pagination.value.page) {
          pagination.value.page = page

          nextTick(() => {
            const { computedRows } = tableRef.value
            selected.value = [computedRows[ Math.min(index, computedRows.length - 1) ]]
            tableRef.value.$el.focus()
          })
        }
        else {
          selected.value = [computedRows[ index ]]
        }
      }
    }
  }
}
</script>
